Humidity will add a darker, blacker patina. Patina typically isn't buffed off in order to preserve its history and value. This is vintage jewelry handmade by Native American Indians. Fred Harvey jewelry is vintage Southwestern jewelry made by The Fred Harvey Company in the first half of the twentieth century.
The company's marketing department chose the jewelry motifs (such as the thunderbird, arrows, and snakes) to appeal to tourists. Even though Native American hands did not typically make the jewelry, the Fred Harvey jewelry style did influence Navajo silversmiths of the day because of its popularity with buyers. Today, authentic Fred Harvey jewelry is collectible in its own right, given its his own context great addition to your collection.